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Concerns about the mercury levels in fish have many people unsure about eating tuna. Although mercury should be a consideration for certain populations, tuna also has several health-promoting nutrients that are worth including in your meal plan. Read on to learn more about the nutritional costs and benefits of tuna and how to incorporate it as part of a healthy lifestyle.

Tuna Nutrition Facts

This nutrition information is provided by the USDA for 1 can (165g) of light tuna, packed in water (without salt) and drained.1

Carbs

Tuna doesn't contain any carbohydrates, fiber, or sugar.

Fats

Tuna is high in omega-3 fatty acids, but low in overall fat, containing less than 2 grams per can for "light" tuna. Different varieties of tuna, however, have different amounts of fat.2 The following common varieties are listed in order from most to least fatty: fresh bluefin, canned white albacore tuna, canned light tuna, fresh skipjack tuna, and fresh yellowfin tuna. 

Protein

Tuna is very high in protein. A can of tuna provides 42 grams of complete protein with all of the essential amino acids.

Vitamins and Minerals

Tuna has calcium, phosphorus, potassium, zinc, B-vitamins, selenium, and choline. Like other canned foods, tuna can be high in sodium. Compare food labels to find low-sodium products or ones with no salt added.

Health Benefits

Whether you have it fresh or canned, tuna has several health benefits to offer. Here are a few ways tuna might support your health.

Helps Prevent Anemia

Tuna contains folate, iron, and B12. A deficiency in any of these micronutrients can lead to various types of anemia.3 Symptoms of anemia can include muscle weakness, disturbed vision, extreme tiredness, along with a host of more serious complications, like infertility. Tuna helps provide a good nutritional basis for the prevention of anemia resulting from nutritional deficiencies.

Promotes Heart Health

Tuna is a source of heart-healthy omega-3 fatty acids, including DHA and EPA. Tuna-based fish oil supplements have been shown to lower triglycerides without raising other types of cholesterol.4 These results suggest that tuna intake or fish oil supplements, help reduce the risk of cardiovascular disease.

May Reduce Risk of Dementia

Strokes and other vascular brain injuries cause changes in memory, behavior, and cognitive function. Balancing our intake of omega-6 fatty acids with more omega-3 fatty acids (from seafood like tuna) can help slow the progressive development of dementia. The omega-3 fatty acids in tuna compete with pro-inflammatory omega-6s to block inflammation at the cellular level, lowering the risk of vascular cognitive impairment and dementia.5

Counters Age-Related Muscle Loss (Sarcopenia)

Higher polyunsaturated fat intake through foods like tuna is associated with greater lean body mass and grip strength in older adults. Furthermore, essential amino acids (also found in tuna) increase the synthesis of muscle protein and support the retention of muscle mass despite the effects of aging.6 The combination of fatty acids and protein in tuna can be helpful for staying strong with age.

Supports Blood Sugar Control

Tuna is free of carbohydrates and provides beneficial nutrients for diabetes management. The American Diabetes Association has listed fish high in omega-3s, including albacore tuna, on their list of top 10 superfoods. They officially recommend eating fish twice per week to help manage diabetes.7

Allergies

Fish is a common allergen that may cause severe reactions, like anaphylaxis.

Sometimes fish allergies can be confused with scombroid poisoning which is actually a histamine toxicity,8 which is not an allergy but rather a form of food poisoning. Tuna is naturally high in histamine. If tuna has spoiled, the overgrowth of bacteria increases the histamine content and likelihood of histamine toxicity. Symptoms can occur anytime between 5 minutes and 2 hours after the ingestion of tuna.

Symptoms of histamine toxicity mimic those of a typical food allergy. Symptoms may include wheezing, tongue swelling, diarrhea, faintness, and nausea. When a group of people who ate the same food exhibit symptoms, however, it is more likely to be histamine toxicity than food poisoning. If an individual experiences a reaction, especially more than once after eating tuna, an allergist can confirm tuna allergies.

Adverse Effects

Many types of fish are high in mercury and should be consumed in limited quantities during pregnancy and breastfeeding to avoid harm to the baby. Current recommendations advise 2–3 servings per week, totaling 8–12 ounces total, of a variety of fish. Albacore or white tuna should be limited to 1 serving per week, totaling 6 ounces.9 Raw or undercooked fish should be completely avoided during pregnancy to prevent food poisoning.

Varieties

Tuna can be eaten fresh or canned. Fresh tuna may be found as steaks, frozen fillets, or sushi and sashimi. Canned tuna is packed in water or oil. There are five species most commonly sold commercially.10

Albacore tuna is the type sold as white meat tuna. "Light" tuna is usually skipjack tuna. Yellowfin tuna is sometimes mixed with skipjack in light tuna cans but it is more often sold as "ahi tuna" steaks. For sushi and sashimi, bigeye tuna is popular. The most expensive tuna variety is bluefin tuna. Bluefin is exclusively used for sushi and sashimi.

Storage and Food Safety

If you're buying fresh fish, avoid products that smell fishy, sour, or like ammonia. Fresh tuna has red flesh that should be firm. If indicators are present, check to be sure the fish was stored at the proper temperature. Fresh fish may be sold as "previously frozen" but should always smell fresh regardless. Frozen fish should be rock solid, not bendable.11

Place raw tuna on ice or in the refrigerator right away after purchasing it and use it within 2 days. If you don't plan to use it that soon, wrap tightly in plastic wrap and foil and put it in the freezer. Wash your hands well with soapy water for 20 seconds after handling raw seafood. Sanitize countertops, cutting boards, and utensils after preparing raw fish.

Thaw frozen fish in the refrigerator or in a sealed plastic bag immersed in cold water. It's best to cook raw tuna to an internal temperature of 145 degrees Fahrenheit. If you choose to eat raw or undercooked tuna, choose products that have been previously frozen, which are less likely to contain parasites.11

Unopened canned or pouch tuna can be stored for several years as long as the container remains sealed. For the best product quality, try to consume within a year of purchasing. After opening, place previously canned tuna in a sealed container and store in the refrigerator. Use within 3–4 days. Once canned tuna is opened, it can also be stored in the freezer in an airtight container.

How to Prepare

One of the most popular ways to prepare canned tuna is to make a tuna salad. While delicious, the ingredients contained in most recipes undermine many of the nutritional benefits of the fish. Be mindful of the amount of mayonnaise you use and add in vegetables for extra crunch, vitamins, minerals, and fiber such as onions, green peppers, or celery.

There are countless ways to incorporate tuna into a heart-healthy diet. You can combine tuna with tomatoes, salad greens, cooked green beans, and boiled sliced potatoes for a classic salad Niçoise. Stir a can of tuna into a pot of corn chowder for a delicious tuna bisque. You can even make a delicious cold pasta salad with tomatoes, celery, canned kidney beans, and black olives.

Fresh tuna can be grilled or roasted with butter and lemon. If you prefer raw or undercooked tuna, be sure to go to a well-reputed sushi restaurant. There is always some risk of foodborne illness when consuming raw seafood.